Photographic objective



(No Model.)

E, GUNDLAGH. PHOTOGRAPHE OBJECTIVE.

Patented 00's. 20, 1891.

i Nm@ g aigleof 1'ieldbut are generally required to i UNITED STATES PATENT Fries;

ERNST GUNDLACH, or ROCHESTER,NEW-YORK.

P'HoToGRAPHic oeJi-zcrlvs.

SPECIFICATION forming part of Letters Patent o. 481,609, dated October 20, 1891.

' VYApplication filed September 26, 1890. Serial No. 366,271. (No model.)

To @ZZ whom it may concern,.-4 y

Be it known Athat I, ERNST GUNDLAOH, of Germany, residing at Rochester, in the county of Monroe and State of New York, have invented a new and` useful Improvement in Photographicv Objectives; and l do hereby declare that Ith'effollowi ng is a`-fullclear, and exact description of the same.

My invention relates to such photographic objectives or lenses which are to be used with diiferent openings or diaphragms, according to light, distance of object, angle of field, and other` circumstances. Such objectives are most generally composed of f-wo achromatic lenses, which are mounted rigidly onto the ends of a tube and in such a distance from each otherlas ismost favorable to the special pnrpfeseotvthe objective, the diaphragm belenses. -Such most favorable distance of the diameter of the diaphragm.11sed,and also ywith the angle of field to be embraced by the l obJec'tive. For instance, in landscape-lenses, 25

which require a wide angle ofield and are `1n`ostly used with/small diaphragme, the best photographic result is 'obtained -With a comparatively short distance of the lenses from cach other or from' the diaphragm, while-in portrait-lenses, which liave'a much smaller wol-l; with comparatively Wide openings or large diaphragms, the distanceiof the lenses Y is-to be correspondingly great, in order to yprod-nce the least possible focal distortion at or near the edges of the picture. 'In fact, if

' the-distance of the lenses is so regulated that l. The objectivewill with `a small diaphragm produce the best possible picture, it will work veryunsatisfactory wi th a large diaphragm,'

,y producing a curved'field and much distortion at the sides. If, however, the lenses are .f brought fartherapar't-toa certain point, so as L Y to have the most favorable position for a large diaphragm, then the picture produced with` Suchpwill certainly showeonsiderable improvement, While on the'Lot-her hand it would' be ,much infcriorif, at this positionof `the lenses, .a small diaphragm were used. Asimilan relation existsfbetween the angle of eld and-the distanc'eof the-lenses. 1 The wider an anglethe 1 objective is to embrace the nearer the lenses the tlatness of the field, and thus to reduce,

these errors, which certainly increase with the angle, to a minimum. Thus a short distance of the lenses will adj ust the objective for small diaphragm and Wide angle and a long, distance for large .diaphragm and narrow angle at the same time.` Furthermore, if the object is very near to the objective and the diaphragm* of the latter is large- -as is, for instance, generally the case with the portrait-objective-then the propel" orU most favorable distance of the lenses 0f the 'objective also'varies considerably with the 'distance of the object, and still more with the difference of the distances of different parts of the object. If, for instance, a person is to be taken in a sitting position, the hands are vusually much nearer to .the objective than the face, and, consequently,if

'the image of the latter appears sharply defined on the focusing-screen the hands are" lout of focus, the latter being` too long and lying behind the plane of the imagc. Provided, then, the image of the hands is near the edge and the face at or near the centerof the picture, the defect could be remedied by bringing fthe lenses of the objective nearer together, in lorder to shorten the oblique focus or that 'which `forms the image of the hands. Thus' in this particular orexceptional case ashorter distance between the lenses thanthat most favorable for gene'ral purposes would be proper.

The object ofmy invention is to provide for suitable means of vconveniently varying the distance of the lenses of vthe photographic objectivefrom each other or from the diaphragm at will, solthat the same maybe ex presslyand accuratelyadj usted for any size of ldiaphragmgand also for any angle of field or size of picture, if required, or, as inthe case of theportrait-objective, for any distance ot' objectfor d iier'ence'of distances of dierent parts of the object. I accomplish'thisend in several ways, Whichrl descr'rbe as follows:

The accompanying drawings illustrate 1n invention in the most accomplished fprm,

' showing Am y new adjustment as being immeloo diatelycc'mbined' with `a so-called` l5 iris dia'` pnragm, so as to act automatically in accordance with the diaphragm when the latter is operated.

Figures 1 and2 are longitudinal -sections of 5 the objective, Fig. 1 showing the adjustment j bined.

The lenses A and 1B a-re secured to the re,

^ A, B, and C are the constituents of the objective, A being the lfront lens, B the back.

lens, and C the diaphragm of the same.

a a is the case'ofv the iris diaphragm, carrying at its sides the, tubes b and c, which are .irmly secured to the same and inclosing the revolving plate q'and the blades, usually eight in number, 0 which'only one lo is shown inthe drawings.A The blades are with oneY end hinged symmetrically around the center of the apparatus at Z, and at the other end j theyare connected with the plate q in such a manner as to form an approximately round opening, which is contracted by turning the plate. one way or widened by turning the other way.`

The'turning is eiected from the outside by the corresponding turning of the ring e with which the plate is connected by the pin h in the usual manner. This concludes the necessary description of the well-known iris diaphragm and the other known or old parts of the apparatus, while in the following A.I describe onlythose parts which embody my invention. j.

l The ring e is united 'with` the ring y by means of the projections a: and which are connected with the corresponding projections fand j" of the ring y. The rings areeach provided with afemale screw w lw', which actuate the corresponding male screws of the ,sliding tube m and the ring g, respectively.

One of the screws is right-handed', the other- 4 left-handed. The tube m is loosely fitted ou the fixed tube b, and is provided with a little block s, which'slides inthe rectilinear slot o.

The' tube'i, which is loosely titted inside of the tube. c, is connected with the ring g by means of the pinsp p',which slide in the respective rectilinear slots n n" of the tube c.

spective sliding tubes m t' by means of their cells u c. v x

When the 'ringe is turned one -way or the other, the opening of the iris diaphragm will in the well-known manner contract or widen, according to the direction of the turn, and at the same time the tubesm and will slide in opposite directions, thus lengthening or shortening the distances of 'the lenses A and B .,Fig. 4 is an objective havingl seneca from the'diaphragm C, and, owiugtothe com'esponding arrangementot the screws w w", these motions will be inthe required accordance to the changes of the diaphragmviz: the lenses will move toward the diaphragm when the opening of the latter is diminishing and-separate when the same is widening, while the threads of the screws arel properly chosen to so regulate the rate of the motion that with any size of aperture of the diaphragm from the largest to the smallest the lenses will attain the proper positionstor the best possible correctionof the field. This willA also be true with the angle of field, since vnot only the diaphragm is to be the smaller, but, for the best possible correction of the optical errors also, the distance of the lenses to beshorter the wider an angle of view the photographic picture to be taken with the objective is to represent. need be paid to the adjustment in operating this apparatus; but the simple regulation of the size of the diaphragm in the usual mannerwi-ll suffice and automatically place the lenses in the proper position. In fact, whatever the outside conditions maybe it is-im possible .to use this objective otherwise than at its best possible performance, provided the size of the diaphragm is properly adj usted and adapted to the case. It -must, however, notbe understood from the descriptionof my automatic adjustment in combination with- `the iris diaphragm that I claim the iris diaphragm itself or any other similar device or any improvement-thereof to form a part of my invention; but my improvement of the Thus no attention IOO photographic Objective consists merelyin the x Y special arrangement for varying and adjusting the distance of the lenses and in the com-'- bination of the same with the irisdiaphragm in such a manner that, the adjustment may4 act automatically when the diaphragm is operated in the usual manner. Also,m y adj ustlos ment device or its purpose must not be confounded-with any kind of focusing arrangement, as the focusing is certainlyand apart Iandindependently from my new adjustment required in the use Aet' my objective, same as in'ordiuary objectives.

Although the iris diaphragm-is probably the best adapted to actin combination with my automatic adjustment, l do not limit myselt` to th's particular type; butany other mechanism in which the size of the diaphragm is regulat l in a similar or suitable way may be employed for the purpose in place of the same. Nor do Ilimi't myself -to the special device of'the adjustment itself, as described,` since many changes in the same are admissible and may even offer advantages to some special requirements, Furthermore, my invention -is by no means confined to the compound ob-` jective-that is, to such which consist of two lenses, one in front andthe other backof the diaphragm, in the drawings; with equal advantages,

izo'

as described and illustrated but it mayjust as well, andbe applied to thesinv of the lenses Y tubes.

,more interchangeable tubes l' of different lengths and arrange the saine so as to carry or receive diaphragms of dilerent sizes, in the usual manner, orto carry one fixed diaphragm of the eXactsize, corresponding to the distance io be secured by the respective- Second. l provide the diaphragm-tube withv sliding tubes, wliich`aie to carry the lenses, similar to those illustrated in the' drawings, but without the adjusting-screws lw w, so that the diaphragm and the lenses are to be ad-v j usted separately.

Third. Instead of adjusting both lenses it will, under certain circumstances be suicient and even more convenient to adjust the distance between the lenses by the movement of the front `lens only. In this case l secure the 'back leiisdirectly to the diaphragm-tube; as

usual. This arrangement will also apply to the automatic adjustment described.

Fourth'.y In order to facilitate the finding of the `proper*-position of the lens or lenses l provide the-adjustment With in,dex and gradita'- A tion, indicating the exact position ot the lens,

orlenses for any given size of diaphragm.

Fifth.v In order to facilitate 'the moving of the sliding tube or tubes, l provide the saine with rack-and-pini'on or any suitablescrew or lever arrangement to be operated by hand.`

Any ot' the above-described devices inay also be applied to the single objective, saine as the automatic mechanism. Y

Fig. 4 of the accompanying drawings reuresents a compound objective which is ad- .justable for dierent angles of eld or.

sizes of picture, auditor diiterent distances of object, as well .as for dierent apertures of diaphragm, the latter adjustment being automatic, saine as in Fig.' 1, but moving only the front lens A,- while the movement of the back lens B is not connected with the iris diaphragm C,"and is to-loe operated independently'from the saine by hand, For

this purpose the screw-ring yn n is provided with a rim h,whicli is milled at its edge.

The ltube or ring i`,`to which the back lens .'60 f, and connectswith the screw s of the outer B is attached, slides inside ofA the tixed tube ring 'ri-fn by a .screw-threaded rim which visipartly cut away so as to leave four equal sections@ n e, (the latter being indi- 'cated-bydotted lines, the fourth not'being shown in the drawiiigs,) which project through the corresponding slots r' r rf', cut in longitudinal direction into the iixed tnlte j. 'lhus the projecting sections o i1' n will slidein their slots along the edges ot` the saine and move the lensB in the direction ot' the' optical axis of the apparatus when the outer ring 7i is turned by handone way or the other. The latter is at n provided with a graduation inarkedwith the diterent sizes of .picture to bevinade with the objective, and.

'the overlapping edge c of the iixed ring p has an index 'to which the graduation is set. rllie'saine movement may also serve to adjust the objective for diit'erent distances of the object at the saine time. For this purposethe dried edge c, instead ot having only an index, is to be providedwith a full graduation, f similar to that ofthe ring n,"but marked with figures indicating the different distances ot the objects. To adjust them, the objective for a certain desired size ot' picturev and ioi distance of object at the. same time, thefcor#k responding line'sof both gradiiatioiis bearing the' respective markings are made to coincide by turning the rim h.

higz is a wide-angle objective having a non-automatic adjustment for the correction ot optical errors at dilterent angles of field, as well as diierent sizes ot diaphragm. Vide-angle objectives are usually wei-hing at an excessive angle, fand, being rigidlyv mounted and properly adjusted in lengthI for such angle, their use is practicallyliinited to that only angle or one single size of picture, because for any other sizes the objective will be more or less out of its opticalv correction and produce interior pictures. lt, however,

IOO

the objective is provided with a'n adjustment,

as shown. in Fig. 5, it '"can 'be properly corrected for and thusV adapted to any smaller angle or size oi' picture, whereby its practical utility is greatly increased. i The Fig. 5 is chosen to represent the case where only one lens A is inade movable, while the other is in a dried position. The adjustment is oper-V ated by turning the `hood a by hand at its milled rim 7i. The hood carries` the lens A, and is provided with a screw s, which screws into thne front extension of the body t. The

latter carries the back lensB and holds the-'' saine in a fined position. 'lhus when the hood a is turned one way or theother the screw s screwed' into the revolving ring e and extends inward through .a slot 'r cutin transversal direction into the body t, whence it reaches and guides the inner revolving plate q of'thediaf phragni, with which the blades are connected, Ysaine as in Fig. l. The iixed ring d serves as .a shoulder against the revolving ring e, holding the saine in its plaee.- Theprojeeting' ring o of the hood doverlaps the fixed ring d, and both are provided with graduations, that of c being-marked with the different sizes of i coincides With the line of d, marked with the size of diaphragm vto be used, when the dis; tance of the lens A and B from each other will be just right for bot-h the size ot' the picture and the diaphragm at the saine time,

same as in Fig. 4. The proper setting oi the diaphragm itself is controlled by a similar graduation marked on the ring e and an index engraved on the body at c.

It must, however, not be inferred from the particular descriptions ot' the several devices which I have adopted in lthe practical embodiment of my invention that the latter is necessarily limited to such details; but, on

the contrary, the principle ot my invention nation, with the fixed or body tube, of-a revmay be utilized through the medium of very' different mechanism, which,however, may be readily devised by any mechanic-'or optician since the principle ofgny invention has been communicated to the public.

What I claim as my invention, and desire to secure by Letters Patent, is

1. In a photographic objective having an adjustable or iris diaphragm, the combination, with the revolublc or operating ring of said diaphragm, of a sliding tube carrying an objective-lens and being connected with said ring by means V4of an external and internal screw, substantially as described and shown. I 2. In a photographic objective having an adjustable lor iris diaphragm, the combination, with the revoluble or 4operating ring of said diaphragm, of a sliding tube carrying an objectivedens and an external and internal screw connecting the sliding tube with the revolubleI ring of the diaphragm, for'` the purpose described.

3. In a photographic objective having an adjustable or iris diaphragm, the combination,

with the revolving or operating ring of said diaphragm, of an internally-screW-threaded sleeve secured to said ring and a sliding tube carrying an objective-lens and having an external screw which fits witnin the threaded `Sleeve, substantially as and for the purpose described and shown. 4. In a photographic objective, the combioluble or operating ring having au internal screw, and a longitudinally-sliding tube ca rryingan objective-lens, and having ,an external screw which fits within the internal .screw of said operating-ring, for the purpose described. Y

' nans'r GUNDLACH.

Viitnesses:r

WM. JOHNSON, DERRICK l/V."Ross. 

